DESCRIPTION (Applicant's Abstract): The broad, long-term objectives of this research are to understand the role which the cannabinoid/anandamide neuromodulatory systems play in both normal physiology and potential pathological states, as well as the effect which the abuse of marijuana has on this neural system. Anandamide (arachidonyl ethanolamide) was the first endogenous cannabinoid-like compound to be identified in brain. While purifying anandamide, two other brain constituents were detected which also displayed cannabinoid-like activity in both a radioligand binding assay and an in situ assay of cannabinoid activity, the inhibition of the twitch response of the mouse vas deferens. The first specific aim of the proposed research project is to isolate and identify the structures of these two previously detected cannabinoid-like brain constituents. We will purify these compounds from porcine brain using column chromatography, and use a radioligand binding assay to screen for cannabinoid-like activity. Active fractions will also be tested for their ability to act as cannabinoid agonists in the mouse vas deferens twitch response. Purified compounds will be analyzed with nuclear magnetic resonance spectroscopy and mass spectrometry for structural determination. Structures will be confirmed by synthesis. Since this new neuromodulatory system is probably involved in such phenomena as memory, emotions, pain, perception and movement, identifying the natural ligands for the cannabinoid receptors may help us to understand disorders of these systems. Anandamide has also been demonstrated to produce several effects which do not appear to be mediated through the cannabinoid receptor. Nor-binaltorphimine (a kappa opioid antagonist) blocks intrathecal cannabinoid antinociception but not that of anandamide. Using the mouse tail-flick test, we will perform a structure activity relationship of this phenomenon. The specific aim is to develop more potent agents, selective for this response, which can then be used to characterize this new binding site. The long term objective is to develop clinically useful analgetic compounds which do not have the side effects of opioid or cannabinoid drugs.